GENETIC DIVERSITY IN NORTH-AMERICAN GINSENG (PANAX-QUINQUEFOLIUS L) GROWN IN ONTARIO DETECTED BY RAPD ANALYSIS

Genetic diversity within North American ginseng (Panax quinquefolius L .) grown in Ontario was investigated at the DNA level using the random ly amplified polymorphic DNA (RAPD) method via the polymerase chain re action (PCR). A total of 420 random decamers were initially screened a gainst DNA from four ginseng plants and 78.8% of them generated RAPD f ragments. Thirty-six of the decamers that generated highly repeatable polymorphic RAPD markers were selected for further RAPD analysis of th e ginseng population. With these primers, 352 discernible DNA fragment s were produced from DNA of 48 ginseng plants, corresponding to an ave rage of 9.8 fragments per primer, of which over 45% were polymorphic. The similarity coefficients among the DNA of ginseng plants analyzed w ere low, ranging from 0.149 to 0.605 with a mean of 0.412, indicating that a high degree of genetic diversity exists in the ginseng populati on. Lower levels of genetic diversity were detected among 3-year-old g inseng plants selected on the basis of greater plant height than among the plants randomly selected from the same subpopulation or over the whole population, suggesting that genetic factors at least partly cont ribute to morphological variation within the ginseng population and th at visual selection can be effective in identifying the genetic differ ences. The significance of a high degree of genetic variation in the g inseng population on its potential for improvement by breeding is also discussed.